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Mom, Dad… There’s something you need to know… I’m a MAMMAL!. Origin of Species Chpt. 24. “That mystery of mysteries…”. Darwin never actually tackled how new species arose….

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Mom, Dad… There’s something you need to know… I’m a MAMMAL!

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Mom dad there s something you need to know i m a mammal

Mom, Dad…

There’s something you need to know…

I’m a MAMMAL!

Origin of Species

Chpt. 24


Mom dad there s something you need to know i m a mammal

“That mystery of mysteries…”

Darwin never actually tackled how new species arose…

Both in space and time, we seem to be brought somewhat near to that great fact—thatmystery ofmysteries—the first appearance of new beings on this Earth.


Mom dad there s something you need to know i m a mammal

origin of new taxonomic groups

Macroevolution macroevoluti macroevolu macroevo


Mom dad there s something you need to know i m a mammal

origin of new species

speciation

speciati

specia

spec


Mom dad there s something you need to know i m a mammal

HOW??

speciation - origin of a new speciesKEYTO MACROEVOLUTION!!


Mom dad there s something you need to know i m a mammal

Anagenesis= one species transforming into oneother species

Nobiologicaldiversity created

speciation= origin of a new species


Mom dad there s something you need to know i m a mammal

Cladogenesis= one species transforming into more species

Biological diversity created

speciation=origin of a new species


Mom dad there s something you need to know i m a mammal

SPECIES


Mom dad there s something you need to know i m a mammal

SPECIES

potential to interbreed

produce viable offspring


Mom dad there s something you need to know i m a mammal

So…what is a species?

  • Biological species concept

    • defined by Ernst Mayr

    • population whose members can interbreed & produce viable, fertile offspring

    • reproductively compatible

Distinct species:songs & behaviors are different enough to prevent interbreeding

Eastern Meadowlark

Western Meadowlark


Mom dad there s something you need to know i m a mammal

Question

How many species of African Violets are here?

SPECIES


Mom dad there s something you need to know i m a mammal

What factors/ barriers can isolate gene pools?

mixing


Mom dad there s something you need to know i m a mammal

What factors isolate gene pools?


Mom dad there s something you need to know i m a mammal

Prezygotic

Barriers


Mom dad there s something you need to know i m a mammal

What factors isolate gene pools?


Mom dad there s something you need to know i m a mammal

What factors isolate gene pools?

Habitat Isolation


Mom dad there s something you need to know i m a mammal

  • allopatric

    • geographic separation


Mom dad there s something you need to know i m a mammal

What factors isolate gene pools?

Temporal Isolation


Mom dad there s something you need to know i m a mammal

Temporal isolation

  • Species that breed during different times of day, different seasons, or different years cannot mix gametes

    • sympatric

      • reproductive separation

Eastern spotted skunk (L) & western spotted skunk (R) overlap in range but eastern mates in late winter & western mates in late summer


Mom dad there s something you need to know i m a mammal

What factors isolate gene pools?

Blue footed boobies mate only after a courtship display unique to their species

Behavioral Isolation

  • reproductive isolation


Mom dad there s something you need to know i m a mammal

What factors isolate gene pools?

Behavioral Isolation

  • reproductive isolation


Mom dad there s something you need to know i m a mammal

What factors isolate gene pools?

sympatric speciation?

Even in closely related species of plants, the flowers often have distinct appearances that attract different pollinators. These 2 species of monkey flower differ greatly in shape & color, therefore cross-pollination does not happen.

Mechanical Isolation

Plants


Mom dad there s something you need to know i m a mammal

What factors isolate gene pools?

sympatric speciation?

Animals

  • For many insects, male & female sex organs of closely related species do not fit together, preventing sperm transfer

    • lack of “fit” between sexual organs: hard to imagine for us… but a big issue for insects with different shaped genitals!

Mechanical Isolation


Mom dad there s something you need to know i m a mammal

What factors isolate gene pools?

sympatric speciation

Gametic Isolation


Mom dad there s something you need to know i m a mammal

Gametic isolation

  • Sperm of one species may not be able to fertilize eggs of another species

    • mechanisms

      • biochemical barrier so sperm cannot penetrate egg

        • receptor recognition: lock & key between egg & sperm

      • chemical incompatibility

        • sperm cannot survive in female reproductive tract

Sea urchins release sperm & eggs into surrounding waters where they fuse & form zygotes. Gametes of different species— red & purple —are unable to fuse.


Mom dad there s something you need to know i m a mammal

PostZygotic

Barriers


Mom dad there s something you need to know i m a mammal

What factors isolate gene pools?

Reduced Hybrid Viability


Mom dad there s something you need to know i m a mammal

What factors isolate gene pools?

Reduced Hybrid Fertility

ex. mules


Mom dad there s something you need to know i m a mammal

Reduced hybrid fertility

  • Even if hybrids are vigorous they may be sterile

    • chromosomes of parents may differ in number or structure & meiosis in hybrids may fail to produce normal gametes

Mules are vigorous, but sterile

Horses have 64 chromosomes

(32 pairs)

Donkeys have 62 chromosomes

(31 pairs)

Mules have 63 chromosomes!


Mom dad there s something you need to know i m a mammal

What factors isolate gene pools?

Hybrid breakdown

F1 fine, subsequent… no good


Mom dad there s something you need to know i m a mammal

Hybrid breakdown

sympatric speciation?

  • Hybrids may be fertile & viable in first generation, but when they mate offspring are feeble or sterile

In strains of cultivated rice, hybrids are vigorous but plants in next generation are small & sterile.

On path to separate species.


Mom dad there s something you need to know i m a mammal

How does Speciation Occur?


Mom dad there s something you need to know i m a mammal

=AllopatricSpeciation

ex. Adaptive radiation


Mom dad there s something you need to know i m a mammal

ex. Adaptive radiation


Mom dad there s something you need to know i m a mammal

ex. Adaptive radiation


Mom dad there s something you need to know i m a mammal

ex. Adaptive radiation


Mom dad there s something you need to know i m a mammal

ex. Adaptive radiation


Mom dad there s something you need to know i m a mammal

ex. Adaptive radiation


Mom dad there s something you need to know i m a mammal

ex. Adaptive radiation


Mom dad there s something you need to know i m a mammal

  • Polyploidy

    2N 4N

    =SympatricSpeciation

TEMPO of evolution


Mom dad there s something you need to know i m a mammal

BIG changes occur b/c of the accumulation of small changes

  • Polyploidy

    2N 4N

    =SympatricSpeciation

GRADUALISM


Mom dad there s something you need to know i m a mammal

  • Polyploidy

    2N 4N

    =SympatricSpeciation

TEMPO of evolution


Mom dad there s something you need to know i m a mammal

  • Polyploidy

    2N 4N

    =SympatricSpeciation

Big changes as it “buds” from parent species, few changes after that

Stephen J. Gould – 1972


Mom dad there s something you need to know i m a mammal

change in rate & timing of developmental events in various parts of the body

how did we differentiate

????????


Mom dad there s something you need to know i m a mammal

change in rate & timing of developmental events in various parts of the body

how did we differentiate????????

If these genes are altered, the timing of development and rate will be altered within the species


Mom dad there s something you need to know i m a mammal

change in rate & timing of developmental events in various parts of the body

how did we differentiate????????

If these genes are altered, the timing of development and rate will be altered within the species


Mom dad there s something you need to know i m a mammal

Hox Genes

1983 -Dr. Thomas Kaufman - Indiana University discovered

Clusters of genes, involved in the regulation of development of animals, plants, fungi


Mom dad there s something you need to know i m a mammal

Hox

Genes

Evolved in the paleozoic era


Mom dad there s something you need to know i m a mammal

Hox Genes

If mutated… OOPS


Mom dad there s something you need to know i m a mammal

antennapedia, a mutation of the Hox Gene that turns the antenna of a fly into a leg.


Mom dad there s something you need to know i m a mammal

Hox Genes

Clusters of genes, that determine where limbs and other body segments will grow in a developing fetus or larva


Mom dad there s something you need to know i m a mammal

Hox Genes

When these genes are altered, positioning varies

Clusters of genes, provide positional info in the embryo


Mom dad there s something you need to know i m a mammal

Hox Genes

When these genes are altered, positioning varies

Clusters of genes, provide positional info in the embryo


Mom dad there s something you need to know i m a mammal

So, if we are connected, how did we differentiate???

Evolution is not the survival of the fittest. Rather it is the survival of the just good enough.


What drove human evolution

What drove Human Evolution?

http://www.npr.org/templates/story/story.php?storyId=124906102


Mom dad there s something you need to know i m a mammal

Summary

  • Be able to discuss the main theories of what is a “species”.

  • Know various reproductive barriers and examples.


Mom dad there s something you need to know i m a mammal

Summary

  • Know allopatric and sympatric speciation.

  • Be able to discuss gradualism and punctuated equilibrium theories.


Mom dad there s something you need to know i m a mammal

Summary

Recognize various ideas about the origin of evolutionary novelties.


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